This application is related to Japanese, Patent Applications No. 2001-042033 filed on Feb. 19, 2001 whose priorities are claimed under 35 USC xc2xa7119, the disclosure of which is incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a donor sheet for a thin-film formation, a process for production thereof and an organic electroluminescent device.
2. Description of the Prior Arts
A thermal transfer process has recently been known as one of the processes for forming a thin film. This process includes fixedly adhering a donor sheet for forming a thin film, that comprises a light-to-heat conversion layer and a transfer layer laminated in this order on a sheet serving as a base material, to a substrate, irradiating laser light from the back- surface of the donor sheet, converting the laser light into heat by the light-to-heat conversion layer, transferring the transfer layer onto the substrate with this heat, and removing then the donor sheet to form a thin film onto the substrate.
The donor sheet has a thin transfer layer on its surface. In order to transport the transfer layer without producing defects onto in the transfer layer, such process has been provided wherein the base material sheet is cut into small pieces before forming the transfer layer, followed by forming the transfer layer onto the base material sheet, and then, the obtained small pieces of the donor sheet are transported after drying. However, this process requires a troublesome process of cutting the base material sheet into small pieces before forming the transfer layer. Further, it takes much time to dry the transfer layer during the formation of the donor sheet that requires a large-sized drying apparatus, to thereby entail a problem of low production efficiency. Additionally, each of the cut small pieces of the donor sheet becomes warped, resulting in entailing a problem that the transfer layer cannot be formed with a uniform thickness.
In order to solve the above-discussed problems, an object of the present invention is to provide a process for producing a donor sheet for thin-film formation by forming a transfer layer and subsequently drying the transfer layer while transporting a base material sheet.
According to the present invention, since the process does not include complicated steps such as cutting the base material sheet into pieces, the donor sheet can be produced easily with good productive efficiency. Also, since the donor sheet is transported and dried in a state free from warps or distortions, it is possible to form a homogeneous transfer layer with a uniform thickness. Further, since the donor sheet is produced while being transported by transporting rollers, the transfer layer of the donor sheet can be formed and dried in a small production space. Thereby, the present invention has an excellent effect in reducing the size of apparatuses for producing and drying the donor sheet.
The invention provides a process for producing a process for producing a donor sheet for a thin-film formation comprising:
while transporting a sheet on which a light-to-heat conversion layer has already been formed, forming a transfer layer on the light-to-heat conversion layer and drying the transfer layer.
The invention also provides a donor sheet for a thin-film formation manufactured by a process described above.
The invention further provides an organic electroluminescent device formed by using a donor sheet described above.
These and other objects of the present application will become more readily apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.